1. Food Production and the Environment The Carbon Cycle

3. Carbon dioxide in the air

4. Green plants use carbon dioxide to make their food

5. Carbon dioxide in the air Green plants use carbon dioxide to make their food Green plants are eaten by animals

6. Carbon dioxide in the air Green plants use carbon dioxide to make their food Green plants are eaten by animals respiration

7. carbon dioxide in the air green plants use carbon dioxide to make their food green plants are eaten by animals respiration dead remains of plants and animals

8. carbon dioxide in the air green plants use carbon dioxide to make their food green plants are eaten by animals respiration dead remains of plants and animals decay by fungi and bacteria

9. Decay  Fungi and bacteria are responsible for the decay of dead organisms.

10. Decay  In order to be able to carry out decay, fungi and bacteria need: 1.Oxygen 2.Moisture 3.The correct temperature

11. The Nitrogen Cycle

13. nitrogen in the air

14. fertilizers

15. nitrogen in the air fertilizers waste substances e.g. faeces

16. nitrogen in the air fertilizers waste substances e.g. faeces lightning

17. nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil

18. nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover

19. nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover dead remains of plants and animals

20. nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover dead remains of plants and animals nitrates in the soil

21. fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover dead remains of plants and animals nitrates in the soil denitrifying bacteria in the soil break down nitrates

22. The nitrogen cycle  Living things need nitrogen to make protein.  They can not use the nitrogen in the air  The nitrogen in the air must be changed to nitrates before plants can use it.

23. The nitrogen cycle  Animals get their nitrogen by eating plants.

24. The nitrogen cycle  The roots of some plants (e.g. clover, pea & beans) have swellings called root nodules on them.  Nitrogen-fixing bacteria living in these nodules change nitrogen in the air into nitrates.

25. The nitrogen cycle  The nitrogen-fixing bacteria are essential to maintain the fertility of the soil.  Without them food yields would rapidly fall.